Tear shaping for refractive correction

ABSTRACT

A lens for refractive tear shaping, having a curved lens body with a peripheral edge and a central opening therein. The central opening is shaped and sized and has a tear shaping edge structured to form a tear meniscus within the central opening. The tear meniscus being formed by interaction of a tear film of the eye and the tear shaping edge and having a posterior curvature conforming to an anterior corneal curvature and an anterior curvature. The anterior curvature is dependent on the size and shape of the central opening and structure of the tear shaping edge.

FIELD OF THE INVENTION

The invention generally relates to contact lenses and refractivecorrection by applications of contact lenses or other structures to theeye.

BACKGROUND OF THE INVENTION

Known contact lenses generally cover virtually all of the cornea orcover the cornea centrally while leaving a portion of the peripheralcornea uncovered. Contact lenses known to the Applicant achieverefractive correction because of the optical nature of an opticallytransparent, rigid, semi-rigid or flexible material that refracts lightand thus alters the refraction of light striking the cornea and passingthrough the other optical parts of the eye to an image formed on theretina.

The concept of a tear lens is known to exist in the context ofconventional contact lenses. The tear lens is formed by a layer of tearsbounded on an anterior surface by the back of a contact lens opticalzone and at a posterior surface of the tear lens by the surface of thecorneal epithelium. A tear lens, as understood in this conventionalsense, contributes to refractive correction primarily in the context ofrigid contact lenses. This is because the posterior surface of the rigidcontact lens maintains its shape and curvature independent of the shapeof the cornea and affects the focusing of light in addition to therefractive power of the contact lens. While a tear lens technicallyexists in the context of flexible or soft contact lenses, the effect ofthe tear lens on refraction is negligible because of the generalconformity of the soft contact lens shape to the shape of the cornea.

Numerous possible complications are known to exist with use of contactlenses on the cornea even though modern contact lenses cause fewercomplications than contact lenses of decades ago. The presence ofcontact lenses can lead to stasis and entrapment of the tear film whichcan lead to an accumulation of corneal epithelial waste products in theentrapped tear film. Corneal epithelial waste products in high enoughconcentrations can be toxic to the cells of the corneal epithelium.Mechanical interaction between the posterior surface of the contact lensand the corneal epithelium can lead to abrasion or distortion.Entrapment of solid objects, however tiny between the posterior surfaceof the contact lens and the anterior corneal epithelium can also lead tocorneal epithelial abrasion. Under some circumstances, the reduction ofoxygen available to the corneal epithelium by having the barrier of thecontact lens between the corneal epithelium and the atmosphere can leadto health complications for the corneal epithelium as well.

There is still room for improvement in the arts of refractive correctionby application of lenses to the eye.

SUMMARY OF THE INVENTION

The invention solves many of the above stated problems by providing alens having a central opening which centers on the optical axis of theeye. The central opening is structured such that capillary action formsa meniscus of tears in the opening. According to an example embodimentof the invention, the inventive lens is structured so that a concavemeniscus is formed. The concave meniscus is provided for correction ofmyopia. It is expected that a concave meniscus will form in a relativelylarger diameter opening according to embodiments of the invention.

According to another example embodiment of the application, a convexmeniscus is formed. A convex meniscus is expected to form in a case of asmaller diameter opening in the lens which generally overlies theoptical axis of the eye.

According to another example embodiment of the invention, the opening isnon-circular in structure. For example, an oval opening is expected tocreate a meniscus having a first curvature in a first axis and a secondcurvature in a second axis and thereby permitting correction ofastigmatism by the tear meniscus formed. According to exampleembodiments of the invention, the central opening may be oval in shapeor polygonal having a first axis longer than a second axis to achievethe astigmatic correction.

According to example embodiments of the invention, the cross-sectionalshape of the edge or periphery of the opening may vary when viewed incross-section.

According to an example embodiment, the cross-sectional shape of theperiphery of the opening may demonstrate a thick rim. According toanother example embodiment, the cross-sectional shape of the peripheryof the opening may demonstrate the thin rim.

According to another embodiment, the cross-sectional shape of theperiphery of the opening may demonstrate a straight rim. The straightrim may be substantially radial in orientation as compared to thecurvature of the lens and opening or may be tilted to create an acute orobtuse angle relative to a tangent to the corneal surface.

According to another example embodiment of the invention, the peripheryof the opening may demonstrate a concave shape when viewed in crosssection.

According to another example embodiment of the invention, the peripheryof the opening may demonstrate a convex shape when viewed in crosssection.

According to another example embodiment of the invention, thecross-sectional shape of the periphery of the opening may demonstrate apolygonal cross-section which may be either concave or convex.

According to other example embodiments of the invention, thecross-sectional shape of the rim may vary around the circumference ofthe periphery of the opening. For example, a portion or portions of theperiphery of the opening when viewed in cross-section may be concavewhile other portions may be convex.

According to another example embodiment of the invention, the perimeterof the rim may vary in shape when viewed in an anterior-posteriordirection.

According to another example embodiment of the invention, the perimeterof the rim viewed anterior to posterior may have a smooth continuouscurved shape.

According to another example embodiment of the invention, the perimeterof the rim when viewed anterior to posterior may include indentations inthe rim perimeter.

According to another example embodiment of the invention, the rimperimeter may include appendages extending inwardly from the rim.

According to another example embodiment of the invention, the peripheryof the opening when viewed in an anterior to posterior direction mayhave a circular shape. According to another example embodiment of theinvention, the periphery of the opening when viewed in an anterior toposterior direction may have an oval shape and according to anotherexample embodiment of the invention, the periphery of the opening inviewed in an anterior to posterior direction may have a polygonal shape.The polygonal shape may include a regular polygon or an irregularpolygon shape. The polygon may be generally radially symmetrical or maybe other than radially symmetrical.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an anterior to posterior view of a lens for refractive tearshaping having a circular central opening therein;

FIG. 2 is an anterior to posterior view of a lens for refractive tearshaping having an oval central opening therein;

FIG. 3 is a lens for refractive tear shaping having a polygonal openingtherein;

FIG. 4 is an anterior to posterior view of a lens for refractive tearshaping having a stellate opening with indentations according to anexample embodiment of the invention;

FIG. 5 is an anterior to posterior view of a lens for refractive tearshaping having a stellate opening with appendages according to anexample embodiment of the invention;

FIG. 6 is an anterior to posterior view of a lens for refractive tearshaping having a generally rectangular polygonal opening thereinaccording to an example embodiment of the invention;

FIG. 7 is a cross-sectional view of a lens for refractive tear shapingin situ on a cornea and with a concave tear meniscus according to anyexample embodiment of the invention;

FIG. 8 is a cross-sectional view of a lens for refractive tear shapingin situ on a cornea with a convex tear meniscus according to an exampleembodiment of the invention;

FIG. 9 is a cross-sectional view of a lens for refractive tear shapingin situ on a cornea with a central opening having inward angled edgesand a concave tear meniscus according to an example embodiment of theinvention;

FIG. 10 is a cross-sectional view of a lens for refractive tear shapingin situ on a cornea with a concave tear meniscus and outwardly anglededges according to an example embodiment of the invention;

FIG. 11 is a cross-sectional view of a lens for refractive tear shapinghaving an opening with concave peripheral edges according to an exampleembodiment of the invention with the tear meniscus not depicted;

FIG. 12 is a cross-sectional view of a lens for refractive tear shapinghaving an opening with convex peripheral edges in situ on a corneaaccording to an example embodiment of the invention with the tearmeniscus not depicted; and

FIG. 13 is a lens for refractive tear shaping in situ on a cornea withan opening having polygonal peripheral edges with the tear meniscus notdepicted.

DETAILED DESCRIPTION

Referring to FIGS. 1-13, the invention is directed to lens forrefractive tear shaping 20 wherein refractive correction is achieved orenhanced by the shaping of the tear film.

Referring particularly to FIGS. 1-6, lens for refractive tear shaping 20according to an example embodiment of the invention generally includeslens body 22 having peripheral edge 24 and defining central opening 26.Central opening 26 is surrounded by a tear shaping edge 28. According tothe depicted embodiment, tear shaping edge 28 defines circular centralopening 30. Tear shaping edge 28 can have a number of cross sectionalstructures and shapes as described below.

Referring now to FIG. 2, another embodiment of lens for refractive tearshaping 20 is depicted. The depicted embodiment includes lens body 22having peripheral edge 24 and elliptical or oval central opening 32.Elliptical or oval central opening 32 is bounded by tear shaping edge28.

Referring to FIG. 3, another embodiment of lens for refractive tearshaping 20 is depicted having polygonal central opening 34. Polygonalcentral opening 34 is depicted as an irregular hexagon, howeverpolygonal central opening 34 may have more or less than six sides andsix vertices.

Referring particularly to FIGS. 2 and 3, elliptical or oval centralopening 32 and polygonal central opening 34 may have long axis 36 andshort axis 38.

Referring now to FIG. 4, according to another embodiment, lens forrefractive tear shaping 20 defines stellate opening 40 havingindentations into the material of the lens surrounding stellate opening40. While stellate opening 40 is depicted as circularly symmetrical,stellate opening 40 may also have long axis 36 and short axis 38.

Referring now to FIG. 5, another embodiment of lens for refractive tearshaping 20 is depicted. According to the depicted embodiment, stellateopening with appendages 44 is depicted. Appendages 46 extend inwardlyfrom outer edge 48. While depicted as circularly symmetrical, stellateopening with appendages 44 may also have long axis 36 and short axis 38.

Referring now to FIG. 6, lens for refractive tear shaping 20 withrectangular opening 50 is depicted. Rectangular opening 50 is depictedhaving a particular proportional aspect ratio, however this should notbe considered limiting as the aspect ratio of rectangular opening 50 maybe altered by altering the length of long axis 36 as compared to shortaxis 38.

Referring now to FIGS. 7-13, cross-sectional views of exampleembodiments of lens for refractive tear shaping 20 are depicted.

Referring particularly to FIG. 7, an embodiment of the inventionincluding parallel tear shaping edge 52 is depicted. It is noted thatlens body 22 in the embodiment depicted in FIG. 7 that parallel tearshaping edge 52 is generally parallel on opposing sides of centralopening 26. Also depicted in FIG. 7 is concave tear meniscus 54. Concavetear meniscus 54 affects a negative refractive power due to its concaveshape and is expected to contribute focusing power for correction ofmyopia. It is expected that the concavity of concave tear meniscus 54will vary with the size of central opening 26 and with the depth 56 oftear shaping edge 28.

It is expected that to a certain point smaller diameter of centralopening 26 will create a more steeply curved concave tear meniscusimparting greater negative refractive power and stronger correction formyopia. It is also expected that increasing depth 56 of tear shapingedge 28 will increase negative refractive power to a certain degree. Asdiscussed above, central opening 26 may have various shapes, some ofwhich include a long axis 36 and short axis 38.

It is expected that by judicious selection of the size of long axis 36and short axis 38 that astigmatism may be corrected by creating aconcave tear meniscus 54 having different shape and therefore differingpower on various meridians.

Referring now to FIG. 8, lens for refractive tear shaping 20 havingparallel tear shaping edge 52 is sized and configured to create convextear meniscus 58. It is expected that when the size of central opening26 is reduced to a sufficient degree, convex tear meniscus 58 will beformed in central opening 26. FIG. 8 depicts parallel tear shaping edge52 along with a smaller diameter central opening 26 than does FIG. 7. Itis expected that when the size of central opening 26 and depth 56 oftear shaping edge are appropriate convex tear meniscus 58 will beformed.

Referring now to FIG. 9, lens for refractive tear shaping 20 withanterior acute tear shaping edge 60 is depicted. It is noted thatanterior acute tear shaping edge 60 is arranged so that tear shapingedge 28 narrows from posteriorly-to-anteriorly. Concave tear meniscus 54is also depicted. It is expected that anterior acute tear shaping edge60 will create a more concave tear meniscus 54 thus, creating greaternegative refractive power to concave tear meniscus 54.

Referring now to FIG. 10, lens for refractive tear shaping 20 havinganterior obtuse tear shaping edge 62 is depicted. Anterior obtuse tearshaping edge 62 is structured so that central opening 26 is wideranteriorly and narrower posteriorly. It is expected that anterior obtusetear shaping edge 62 will create a flatter concave tear meniscus 54 asdepicted in FIG. 10 thus, creating a concave tear meniscus having lessnegative refractive power than parallel tear shaping edge 52 having asimilar posterior diameter.

Referring now to FIG. 11, lens for refractive tear shaping 20 havingconcave tear shaping edge 64 is depicted. In FIG. 11, no tear meniscus66 is depicted for clarity. Concave tear shaping edge 64 includesanterior edge 68, posterior edge 70 and concave portion 72.

Referring now to FIG. 12, lens for refractive tear shaping 20 withconvex tear shaping edge 74 is depicted. No tear meniscus 66 is depictedfor clarity. In the depicted embodiment, convex tear shaping edge 74 hasa radius of curvature approximately equal to half of depth 56 of tearshaping edge 20. This should not be considered limiting however as theradius of curvature of convex tear shaping edge 74 may vary.

Referring now to FIG. 13, lens for refractive tear shaping 20 withfaceted tear shaping edge 76 is depicted. Faceted tear shaping edge 76presents anterior edge 78, posterior edge 80 and internal angle portion82.

Lens for refractive tear shaping 20 according to the various embodimentsdescribed herein may be formed from hydrogel polymers of the types usedin soft contact lens that are now available or any hydrogel polymermaterials to be developed in the future. Hydrogel polymers are generallywater absorbent and hydrogel polymers may be used to manufacture lensesfor refractive tear shaping 20 according to the invention by methodsincluding but not limited to lathe cutting, cast molding, spin castingand injection molding. Lenses for refractive tear shaping 20 may also bemanufactured from rigid oxygen permeable materials by knownmanufacturing processes including lathe cutting. It is to be understoodthat lens for refractive tear shaping 20 may be manufactured by anyknown contact lens manufacturing process or contact lens manufacturingprocesses to be developed in the future.

Lenses for refractive tear shaping 20 are expected to be made indiameters ranging from approximately 5 mm to 16 mm. Certain features oflens for refractive tear shaping 20 such as central opening 26 diameter,the structure of tear shaping edge 28, the appropriate length of longaxis 36 and short axis 38 to achieve desired refractive correction areexpected to be developed with a certain degree of experimentation. It isexpected that this degree of experimentation will not be undue and thatthose of ordinary skill in the art based on the present applicationdisclosure will be able to engage in such experimentation withoutsignificant difficulty.

It is expected that for formation of concave tear meniscus 54, thatsmaller diameter central openings 26 will result in higher refractivepower of concave tear meniscus 54, thus permitting higher degrees ofrefractive correction for myopia. It is also expected that when thediameter of central opening 26 becomes sufficiently small, tear meniscus66 will transition from concave tear meniscus 54 to convex tear meniscus58. Determination of this transition diameter for transition is expectedto be achievable by reasonable levels of experimentation.

The effect of depth 56 of tear shaping edge 28 on refractive power oftear meniscus 66 also should be determinable by reasonableexperimentation. It is expected that greater depth 56 will generallycreate a thicker periphery of tear meniscus 66 resulting in higherdegrees to concavity of concave tear meniscus 54 and greater myopiccorrection.

Further, understanding of the effect of other features of the disclosedlenses including anterior acute tear shaping edge 60, anterior obtusetear shaping edge 62, concave tear shaping edge 64, convex tear shapingedge 74 and faceted tear shaping edge 76 are expected to be achieved byreasonable experimentation well within the ability of one of ordinaryskill in the art. It is expected that such experimentation will not beundue. It is also expected that the effect of stellate opening 40 withindentations 42 as well as stellate opening with appendages 44 andappendages 46 can also be determined experimentally.

The present invention may be embodied in other specific forms withoutdeparting from the spirit of the essential attributes thereof;therefore, the illustrated embodiments should be considered in allrespects as illustrative and not restrictive, reference being made tothe appended claims rather than to the foregoing description to indicatethe scope of the invention.

1. A lens for refractive tear shaping, comprising: a curved lens bodyhaving a peripheral edge and defining a central opening therein; thecentral opening being shaped and sized and having a tear shaping edgestructured to form a tear meniscus within the central opening; and thetear meniscus being formed by interaction of a tear film of the eye andthe tear shaping edge and having a posterior curvature conforming to ananterior corneal curvature and an anterior curvature the anteriorcurvature being dependent on the size and shape of the central openingand structure of the tear shaping edge.
 2. The lens for refractive tearshaping as claimed in claim 1, wherein the central opening is circularin shape.
 3. The lens for refractive tear shaping as claimed in claim 1,wherein the central opening is oval or elliptical in shape.
 4. The lensfor refractive tear shaping as claimed in claim 1, wherein the centralopening is polygonal in shape.
 5. The lens for refractive tear shapingas claimed in claim 1, wherein the central opening is stellate in shapeand comprises indentations extending outwardly into an edge of thecentral opening.
 6. The lens for refractive tear shaping as claimed inclaim 1, wherein the central opening is stellate in shape and comprisesappendages extending inwardly from an edge of the central opening. 7.The lens for refractive tear shaping as claimed in claim 1, wherein thecentral opening presents a long axis and a short axis.
 8. The lens forrefractive tear shaping as claimed in claim 1, wherein the tear shapingedge is substantially parallel around a perimeter of the centralopening.
 9. The lens for refractive tear shaping as claimed in claim 1,wherein the tear shaping edge is anteriorly acute when viewed in crosssection such that the diameter of the central opening is greaterposteriorly than anteriorly.
 10. The lens for refractive tear shaping asclaimed in claim 1, wherein the tear shaping edge is anteriorly obtusewhen viewed in cross section such that the diameter of the centralopening is less posteriorly than anteriorly.
 11. The lens for refractivetear shaping as claimed in claim 1, wherein the tear shaping edge isconcave when viewed in cross section.
 12. The lens for refractive tearshaping as claimed in claim 11, wherein the tear shaping edge furthercomprises an anterior edge, a posterior edge and a concave portion whenviewed in cross section.
 13. The lens for refractive tear shaping asclaimed in claim 1, wherein the tear shaping edge is convex when viewedin cross section.
 14. The lens for refractive tear shaping as claimed inclaim 1, wherein the tear shaping edge is polygonal when viewed in crosssection.
 15. The lens for refractive tear shaping as claimed in claim 1,wherein the tear shaping edge when viewed in cross section is consistentin structure about a circumference of the central opening.
 16. The lensfor refractive tear shaping as claimed in claim 1, wherein the tearshaping edge when viewed in cross section is variable in structure abouta circumference of the central opening.
 17. A method of correctingrefractive error of an eye; comprising: applying a contact lens to theeye having a central opening therein; and shaping the tear film withinthe central opening to form a tear meniscus by capillary action betweenthe tear meniscus and a tear shaping edge of the central opening; andmanipulating the tear meniscus formed by varying a size of the centralopening, by varying a shape of the central opening, by varying thestructure of the tear shaping edge or by a combination of varying thesize, varying the shape of the central opening and by varying thestructure of the tear shaping edge.
 18. The method as claimed in claim17, further comprising manipulating the tear meniscus by selecting thecontact lens such that the central opening has long axis and a shortaxis.
 19. The method as claimed in claim 17, further comprisingmanipulating the tear meniscus by selecting the contact lens such thatthe central opening has a polygonal shape.